This invention relates to a bearing assembly for supporting a high speed rotating shaft. More specifically, this invention relates to a bearing assembly having improved means for preventing detrimental bearing vibration.
Bearing design constitutes a major problem in the use of high speed rotating shafts, such as in turbomachinery. That is, bearings for the shaft must be designed for rotationally centering and supporting the shaft at high speeds for prolonged periods of time without excessive vibration or high rates of wear. In turbomachinery, these shaft bearings typically comprise so-called plain bearings or bushings concentrically received over a shaft for supporting the shaft with respect to a housing or the like, and wherein suitable lubrication is provided as by oil inlets in the housing.
With high speed rotating machinery, vibratory movements of the shaft bearings or other machine components can result in rapid destruction of the bearings and corresponding failure of the rotating machinery. These vibrations may result from inherent machine imbalances, attainment of natural resonance frequencies, or a combination of these factors. In the prior art, vibration problems in the machinery have been approached by attempts to secure or lock the bearings in position. See, for example, U.S. Pat. Nos. 3,040,590 and 2,683,637 which show the use of fluid dampers and the like. Other techniques have included securing the bearings against rotation and/or axial motion within a housing as by means of locking springs, antirotation pins, or press-fit relationships between the bearings and the housing. See for example, U.S. Pat. Nos. 3,563,619; 2,532,795; and 1,562,644. However, these bearing locking techniques inherently subject the bearings to uneven axial and/or rotational wear, and non-uniform exposure to elevated temperatures. Moreover, the pins or springs themselves may vibrate or fail such as when their resonant frequencies are reached to set up corresponding vibrations in the bearings. All of these factors contribute to shortened bearing life making prior art bearings in high speed rotating machinery unsatisfactory for prolonged operation.
This invention overcomes the problems and disadvantages of the prior art by providing a bearing assembly including means for securing a sleeve bearing against detrimental vibration while allowing carefully controlled axial floating and relatively slow rotational floating of the bearing for uniform wear and temperature distribution.